1. Field of the Invention
The present invention relates to a composition comprising a poorly soluble drug, a water-soluble macromolecular compound and a biodegradable macromolecular compound. More particularly, the invention relates to a composition comprising a poorly soluble drug, a water-soluble macromolecular compound and a biodegradable macromolecular compound and as such insuring increased solubility and well controlled release of said poorly soluble drug.
2. Description of Prior Art
It is known that in the administration of a poorly soluble drug, the rate of dissolution of the drug is determinant of the rate of absorption of the drug in many instances and that the solubility of the drug has a profound influence on the bioavailability of the drug. A diversity of methods have been proposed for enhancing the dissolution rate of poorly soluble drugs. There are reports, for instance, on the preparation of a coprecipitate between a poorly soluble drug and a highly water-soluble macromolecular substance such as polyvinylpyrrolidone and the use of the coprecipitate as an oral medicine [Shotaro Sakurai et al.: The Archives of Practical Pharmacy, 47, 191-196 (1987) or a suppository (Yoshiko Hamamoto et al.: The Archives of Practical Pharmacy, 49, 209-214 (1989)].
It is true that the dissolution of the poorly soluble drug from such a coprecipitate prepared by these prior art technologies is rapid indeed but the rate of release of the drug can hardly be controlled. Therefore, there are defects that it is impossible to supply the recipient body with a sufficient amount of the drug to maintain a therapeutically effective concentration and thus its sufficient efficacy cannot be expected. Moreover, the risk has been pointed out that the rate of release may sometimes be so rapid that more than the necessary amount of the drug is released at a time to cause adverse reactions.
Under the circumstances the development of a therapeutic system (composition) insuring enhanced solubility and controlled release of a poorly soluble drug has been keenly demanded in the pharmaceutical field.
Accordingly, in view of these circumstances, the inventors of the present invention explored this field of technology with due diligence for establishing a composition which would be free from the above-mentioned disadvantages and capable of insuring enhanced solubility and well controlled release of a poorly soluble drug and discovered that these requirements can be met by providing a composition comprising a poorly soluble drug, a water-soluble macromolecular compound and a biodegradable macromolecular compound. This finding was followed by further research, which has culminated in the present invention.